Inspection Tools

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View of Panda-Style PM Fiber with the FS201 Inspection Scope and FS201-PM Adapter

• Critically Examine Fiber Polish Quality
• Scope Includes Two Fiber Adapters:
  • FS200-FC: FC/PC, FC/APC, ST^®/PC, and SC/PC Connectors
  • FS201-SMA: SMA905 and SMA906 Connectors
• Additional Connector Adapters Sold Separately Below

The FS201 Fiber Inspection Scope produces a high-quality, low-distortion image of both the fiber end and surrounding ferrule. With a high-intensity illumination system and 200X magnification, this microscope is powerful enough to offer a clear image of the fiber core as well as the surrounding cladding. The FS201 offers both coaxial and oblique illumination settings. The coaxial setting provides symmetric lighting for high-detail inspection, and the oblique setting provides light at an off-center angle to the fiber end face for higher contrast.

The FS201 includes the FS200-FC adapter for FC-/ST-/SC-terminated fibers (Ø2.5 mm ferrules) and the FS201-SMA adapter for SMA905- and SMA906-terminated fibers (Ø3 mm ferrules). The FS200-LC adapter for LC-terminated fibers (Ø1.25 mm ferrules) and the FS201-PM for polarization-maintaining fibers are available separately below.

Fiber Scope Operation
Insert the fiber connector into the adapter until it stops and then firmly hold in place during inspection. To activate illumination, flip the switch on the bottom of the scope; "|" activates coaxial illumination, while "||" activates oblique illumination. Once finished, flip the switch back to "O" to turn the scope off.

To inspect the full surface area of fibers with larger cores or fibers with angled faces, it may be necessary to rotate the fiber connector. This is also useful for differentiating between contaminants on the face of the fiber connector and those on the scope optic itself. In order to see the entire field of view, the rubber eyepiece should be as close as possible to the operator's eye. Operators who normally wear eyeglasses should remove them to fully inspect the fiber. Please note that under normal operation, the focus adjustment knob should not be rotated to its limits. Doing so repeatedly may cause the unit to fail over time.

Adapter Alignment
Although each adapter comes pre-aligned for use with the FS201, it may be necessary to align the adapter to center the fiber in the field of view for fibers with poor centration. First, follow the basic steps above to inspect a test fiber. Using a 1.5 mm hex key or balldriver, loosen the three setscrews around the edge of the connector adapter at the end of the scope. Look through the illuminated scope, focus on the fiber ferrule, and align the connector until the ferrule face is centered within the field of view. Progressively adjust the three setscrews until the end face is in the center of the scope view.

Connector Adapters for the FS201 Fiber Inspection Scopea
Photos (Click to Enlarge)
Item #	FS200-FC	FS201-PM	FS201-SMA	FS200-LC
Compatible Connectors	FC/ST/SC	PM FCb	SMA905 SMA906	LC
Included with FS201	Yes	No	Yes	No

• All of these adapters are also compatible with the FS200 Fiber Inspection Scope. 
• This adapter features a v-groove aligned with the FC connector key on polarization-maintaining patch cables. However, It is also compatible with standard FC, ST, and SC connectors.

• Connector Adapters Compatible with the FS201 Fiber Inspection Scope
• Options Available for FC, ST, SC, SMA905, SMA906, or LC Connector Types
• FS201-PM Adapter Features V-Groove Aligned to Wide Key Slot (2.2 mm) of the FC/PC Bulkhead

These connector adapters are used with the FS201 Fiber Inspection Scope sold above to enable compatibility with different ferrule and connector types (see table to the right for options). The FS201-PM adapter is like the FS200-FC adapter, except it features a V-groove that is aligned with the wide key slot on the FC/PC bulkhead. This provides a rough guide for determining the relative alignment of the connector key to the fiber stress members when used with polarization-maintaining patch cables. 

Although each adapter comes pre-aligned for use with the FS201, it may be necessary to align the adapter to center the fiber in the field of view for fibers with poor centration. First, follow the basic steps above to inspect a test fiber. Using a 1.5 mm hex key or balldriver, loosen the three setscrews around the edge of the connector adapter at the end of the scope. Look through the illuminated scope, focus on the fiber ferrule, and align the connector until the ferrule face is centered within the field of view. Progressively adjust the three setscrews until the end face is in the center of the scope view.

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• Measures SMA905 Ferrule Height Relative to 0.3860"
• Calibration Pin Included
• Detailed Calibration and Usage Instructions in Manual

The 10125HG SMA height gauge is ideal for accurately measuring the height of a polished fiber optic SMA905 connector. SMA-to-SMA couplers are designed to have a non-contact interface, and since the insertion loss (IL) of an SMA-SMA junction is dependent on the distance between the two SMA connector end faces, the height of the polished SMA connector is important. We recommend frequent calibration using the attached calibration pin. For detailed calibration instructions, please see the manual. Please note that this gauge is not compatible with SMA906 connectors.

To use, thread an SMA905-terminated fiber into the port at the bottom of the gauge and hand tighten. The connector height measurement on the gauge face is with respect to 0.3860". The photo above shows a ferrule with a height of 0.3863" which reads as +3 ticks on the gauge face. Be sure the gauge is properly calibrated prior to use.

Please note the IEC standard for SMA ferrule height is 0.3850" to 0.3863" (IEC61754-22).

The graph to the right shows the theoretical insertion loss as a function of the separation of two SMA connectors using our M38L01 patch cable. The fiber in this cable has a core diameter of 200 µm, a numerical aperture of 0.39, and an index of 1.4571 at 633 nm. This graph was generated using the following equation:

where z is the separation distance, a is the radius of the core size in µm, NA is the numerical aperture of the fiber, and n₀ is the index of the core. Click here to download an interactive Excel file which can be used to calculate and graph the theoretical insertion loss for any fiber.

The height gauge should not be used for testing high-power fiber patch cables as the contact between the gauge and connector end can damage the exposed fiber tip.

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The R3L3S1P test target viewed through the EYL10X.

• Magnification: 6X or 10X
• Uses a Pair of Glass Achromatic Doublets
• AR Coating on All Glass-to-Air Optical Surfaces
• Large Field of View: Ø1.4" for 6X and Ø1.1" for 10X
• Small Form Factor

Thorlabs' Premium Eye Loupes provide clear magnification that is ideal for inspecting optics and small parts. The eye loupes were designed by Thorlabs to maximize working distance when used with the knurled edge oriented towards the eye. They use a pair of glass achromatic doublets to minimize chromatic and other aberrations. The AR coating on each optical surface is optimized to reduce internal reflections at wavelengths visible to the human eye. These high-quality magnifiers are suitable for quality control applications in industry or inspecting optics in the lab. They are available in 6X and 10X magnifications.

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This ray tracing demonstrates the virtual image seen through the EYL06X eye loupe.

Eye Loupe Magnification
The magnification specification provided for these eye loupes is determined using the standard magnification definition:

where M is the magnification, H_image is the image height, and H_object is the object height. This definition is valid when used at the specified working distance. When using this equation, the magnification of EYL06X and EYL10X is 6.0 and 10.0, respectively, as specified in the table above.

The maximum magnification that can be achieved on the human retina is given by the loupe magnification definition, which is a thin-lens formula:

where M is the magnification and f is the focal length of the lens in mm. When using this equation, the magnification of EYL06X is 5.5 and the magnification of EYL10X is 8.9.

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The R3L3S1P test target viewed through the JEL10.

• 10X Magnification
• Hastings Design
• Lightweight

This Bausch & Lomb loupe is an ideal, economical tool for inspecting optics and small parts. The eyepiece provides a clear, 10X magnification. This loupe is designed to be used with the flared edge facing the eye. If the JEL10X does not meet your inspection needs, our premium eye loupes (featured above) provide a higher image quality and a wider field of view suitable for industry inspection applications.

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• 2.0X Magnification
• Can be Worn With or Without Eyeglasses
• ESD Compliant

This head-worn inspection magnifier is ESD compliant and cleanroom compatible. It is ideal for inspecting components when high magnification is not required and may be worn with or without prescription eyeglasses. The position of the magnifying lenses is adjustable so that they can be swung out of your line of sight when magnification is not needed.

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Partial Extension of Telescoping Arm

• Corrosion-Resistant Stainless Steel Telescoping Handle
• High-Quality, Low Distortion Ø1.25" Glass Mirror
• Articulated Joint Adds Versatility in Mirror Positioning
• 8.50" (21.6 cm)  Solid Length, 35" (88.9 cm) Extended Length

This telescoping inspection mirror is ideal for viewing components in hard-to-reach areas of the lab.

• Visual Scratch-Dig Reference
• Scratch: Any Marking or Tearing of the Glass Surface
• Dig: A Small Rough Spot on the Glass Surface, Similar to a Pit in Appearance

Scratch-dig paddles are used to determine the cosmetic surface quality of an optic. Thorlabs' SDPK Scratch-Dig Paddle has 7 rectangular sections and 7 circular sections each of which contains a different scratch or a different dig. Scratch-dig refers to the cosmetic quality of the surface of an optic and is defined by the U.S. military (MIL-PRF-13830B). Although not certified, this paddle contains scratch and dig features that can be compared to any optic for classification. To use the paddle, place it next to the optic you are inspecting and compare the imperfections on the optic's surface to the imperfections on the paddle.

Procedure:
The surface quality is to be specified by a number such as 60-40 scratch-dig. The first number corresponds to the max scratch width compared to the reference scratches on the SDPK paddle. It does not correspond directly to a precise scratch width. The next number indicates the mean diameter of a dig in hundredths of a millimeter. The table to the right can be used to quickly convert the dig number into millimeters or inches.